1. Field of the Invention
The invention relates to a manufacturing method of a semiconductor light-emitting apparatus and the semiconductor light-emitting apparatus and, more particularly, to a manufacturing method of a semiconductor light-emitting apparatus using a bonding technique by a soldering layer and the semiconductor light-emitting apparatus.
2. Description of the Related Art
A semiconductor light-emitting apparatus having a structure in which a light-emission operating layer formed on a growth substrate is soldered or bonded to a supporting substrate through an AuSn (gold tin) solder has been known in the related art. As an example of the semiconductor light-emitting apparatus having a bonded structure as mentioned above, a cross sectional view of the semiconductor light-emitting apparatus prior to bonding is illustrated in FIG. 1. As shown in FIG. 1, an Au (gold) layer 102, a Ti (titanium) layer 103, an Ni (nickel) layer 104, and an AuSn soldering layer 105 are sequentially laminated on the surface of a supporting substrate 101. A light-emission operating layer 107, an AuZn (alloy made of gold and zinc) layer 108, a TaN (tantalum nitride) layer 109, an Al (aluminum) layer 110, a Ta (tantalum) layer 111, and an Au layer 112 are sequentially formed on the surface of a growth substrate 106. The Au layer 112 and the AuSn soldering layer 105 are closely adhered so as to face each other and, thereafter, the AuSn soldering layer 105 is heated and cooled, so that the AuSn soldering layer 105 is melted and solidified. By the melting and solidification, the growth substrate 106 formed with the light-emission operating layer 107 is soldered to the supporting substrate 101 through the AuSn soldering layer 105. After the soldering, the growth substrate 106 is removed by etching. The AuZn layer 108 has a function for reflecting light which is emitted from the light-emission operating layer 107 and increasing an extracting efficiency of light.
In order to allow the light emitted from the light-emission operating layer 107 to be further efficiently reflected, a structure of a semiconductor light-emitting apparatus in which a reflection insulating layer is formed between the light-emission operating layer 107 and the AuZn layer 108 has been proposed in recent years (refer to Patent Document 1: Japanese Patent Application Laid-open Kokai P 2006-86208). A SiO2 film (silicon oxide film) or a metal oxide film is used as a reflection insulating layer from a viewpoint of controlling current distribution of the light-emission operating layer 107 and efficiently reflecting the light emitted from the light-emission operating layer 107.
In the semiconductor light-emitting apparatus having the reflection insulating layer mentioned above, the reflection insulating layer is not formed on the whole surface of the light-emission operating layer but a reflection insulating layer in which an opening portion is selectively provided is formed. This is because an ohmic contact with the light-emission operating layer can be obtained by embedding a conductive substance such as a metal into the opening portion of the reflection insulating layer, and a current flowing toward the light-emission operating layer can be controlled and assured by the ohmic contact.
As a method of forming the opening portion into the reflection insulating layer in order to obtain the ohmic contact mentioned above, there is a method whereby a resist which has been patterned by a photolithography technique is formed on the reflection insulating layer which has temporarily been formed on the whole surface of the light-emission operating layer and the opening portions are formed by etching the reflection insulating layer by using the resist as a mask. After that, a thin film of a desired metal, alloy, or the like is formed on the reflection insulating layer by an evaporation deposition method or the like, and the growth substrate including the light-emission operating layer is bonded to the supporting substrate through the thin film.